As it turns out, their fears were completely misplaced; Obama has never shown any stomach for increasing gun control, even after six mass shootings in the space of a year. Like every Democrat since the 2000 election, Obama appears to be terrified of the gun lobby.

But that doesn't stop the National Rifle Association from constantly warning gun owners that the federal government is plotting to take their weapons away. It is an effective sales pitch, one that generates billions of dollars per year for the arms industry that the gun lobby represents. After Obama's re-election this year, nearly two million Americans attempted to buy guns in the month of November.

Here is another well-known sales pitch: after every mass shooting, the first response from the gun lobby is that if only everyone was armed, mass shootings could be prevented. Today, gun advocate John Lott is reported as saying that gun-free zones in schools are "a magnet for deranged killers," and the solution is to arm teachers. To anyone not awash in the fantasies of the gun industry, this argument is repellent. Most people do not want to turn schools, or other public spaces, into armed camps. The prospect of untrained but vigilant citizens shooting down mass killers is the stuff of movies, not reality. Law enforcement officers, who know how difficult it is to hit the right target in a firefight, explicitly warn against it. We should recognise this argument for what it actually is — advertising for guns.

The United States has a well known "gun culture," but this culture has changed noticeably in recent years. The number of Americans who own guns is decreasing, but the number of guns in circulation is rising. About 60 per cent of gun owners have at least one semi-automatic weapon. Semi-automatics, also known as "assault weapons," are designed to kill large numbers of people in battle. They are not traditional hunting weapons, though hunters are using them more and more. They are not the most practical weapons for self-defence. After the Port Arthur massacre John Howard acted to ban semi-automatics, backed by a public consensus in Australia that nobody needed such a thing in civilian life. But in the increasingly paramilitary American gun culture, ownership of assault weapons has become so pervasive that any Australian-style buyback scheme would be practically impossible.

Many Americans also equip their home arsenals with enlarged magazines, allowing them to fire more rounds without reloading, and protective clothing that resembles riot gear. This trend mirrors the militarisation of local policing in the United States. Even small towns now have tactical response units that use armoured vehicles, battering rams, stun grenades and sniper rifles. These units, originally developed for counter-terrorism and hostage crises, have little to do in most American cities. Police departments end up using them for small-time drug arrests, sometimes with disastrous consequences. It is not surprising that some ordinary citizens feel the need to arm themselves to the teeth when the local police look like they are about to confront an invading army.

The six mass shootings we have seen this year are a predictable consequence of the paramilitary turn in American gun culture. Nearly all of the massacres this year have featured multiple assault weapons, usually with enlarged cartridges enabling the killers to fire dozens of rounds before reloading. In some cases the perpetrators have bought the guns themselves, but sometimes they have taken them from a friend or relative's collection. It appears that the Connecticut gunman got his weapons from his mother's extensive cache. She was his first victim. Primary schools are not "magnets for deranged killers," but arsenals of high-powered weapons certainly are.

The paramilitary culture with its combat weaponry is not an inevitable outgrowth of hunting, self-defence, or even the constitutional right to bear arms. It is the result of a deliberate marketing strategy by the firearms industry and the gun lobby, its political wing. It feeds on paranoia and a domestic arms race between law enforcers and hobbyists. A mass shooting every few months or weeks is the price Americans pay for the rights of gun enthusiasts to stock their private fortresses. The NRA and its allies will ensure that they keep paying that price.

Senior Lecturer in American Politics and Foreign Policy, United States Studies Centre (jointly appointed with the School of Social and Political Sciences, University of Sydney)

David Smith is jointly appointed between the US Studies Centre and the School of Social and Political Sciences at the University of Sydney. His research examines political relations between states and minorities, with a focus on religion in the US. His book Religious Persecution and Political Order in the United States was published by Cambridge University Press in 2015.